1. Field of the Invention
The present invention generally relates to a lubricating apparatus for automatically lubricating a chain by being driven thereby and, more particularly, to a checker-arm chain lubricating apparatus suitable for a small-size chain and a high-speed chain having a construction in which a lubricating pump is operated by a checker arm oscillated by the operation of the chain.
2. Description of the Related Art
An apparatus is known as a connveyor chain lubricating apparatus, in which motion of a checker arm oscillated by a traveling chain is transmitted to a plunger of a reciprocating pump unit through a cam for automatic lubrication of the chain.
FIG. 9 shows an example of a conventional chain lubricating apparatus as mentioned above. A lubricating apparatus A1 has a frame A3 fixed at a predetermined position in the vicinity of a travel path of a conveyor chain A2. A checker arm A4 and a cam shaft A6 fixed with a cam A5 are swingably supported on the frame A3.
The checker arm A4 is rotatively arranged at the tip end thereof with a checker roller A8 that abuts against a roller A7 of the chain A2.
The checker arm A4 is arranged such that the roller A7 pushes the checker roller A8 as the chain A2 moves to oscillate forward, thereby allowing the roller A7 to pass. Restoration torque is given by a return spring, not shown, installed on the cam shaft A6 such that, when the checker roller detaches from the roller A7, the checker arm returns again to the position indicated in the above-mentioned figure.
On the other hand, a roller follower A10 linked with a plunger of a reciprocating pump unit A9 is pressed by a spring A11 against a cam face formed around the cam A5. When the checker arm A4 is oscillated forward by the chain A2, a lubricant is taken into the pump unit A9 from a lubricant tank (not shown) which is linked to the inlet port of the pump unit A9 and the lubricant is discharged from the tip of a lubricant nozzle A12 which is linked to the discharge port of the pump unit A9 toward the chain A2 when the checker arm moves to return.
The lubricating apparatus using the conventional checker arm having the above-mentioned construction has been developed for lubricating conveyor chains that are relatively large in size and slow in operating speed. In this lubricating apparatus, the roller follower linked to the plunger of the pump unit is made to follow the profile of the circumferential face of the cam, so that the oscillation angle of the checker arm becomes as large as about 38 degrees, thereby making it hard to operate the plunger at high speeds. This drawback makes a lubricating apparatus of this type unsuitable for a small-size chain having a small pitch between rollers and bushings or for a chain operated at high speeds.
If the chain travels in a reverse direction, the checker arm must be prevented from interfering with the roller of the chain. For this purpose, the lubricating apparatus is required to have an additional mechanism by which a clutch is installed between cam and cam shaft and the checker arm is rotated to a retired position by rotating an operator knob arranged on the cam shaft and a stopper mechanism by which the checker arm is held at the retired position. This increases the number of parts used in the apparatus, making the construction complicated and thus, increasing the manufacturing cost.
In addition, use of the above-mentioned conventional apparatus for a chain that travels in a vertical direction requires the lubricating apparatus to be installed vertically. Such orientation, however, requires that the direction in which the apparatus is bled be taken into account because the movable parts in the lubricating apparatus are generally lubricated by an oil bus. This consequently requires a bleeder pipe to be re-installed.
It is therefore an object of the present invention to provide a checker-arm chain lubricating apparatus that is capable of efficiently and surely lubricating both a small-size chain and a chain operating at high speeds, that is simple in construction, that is low in manufacturing cost, and that can be easily adapted to the chain installed direction.